POSITIVE CTRL 3
The genomic DNA contained in the stool samples was extracted using QIAamp DNA Stool Mini Kit (QIAGEN, Germantown, MD, USA) according to the manufacturers instructions. We measured the concentration and quality of the DNA using a Qubit 2.0 Fluorometer (Life Technologie, USA) and agarose gel to ensure that adequate amounts of high-quality genomic DNA.The V4-V5 region of the bacterial 16S rRNA gene was amplified using the universal primers 515F: GTGCCAGCMGCCGCGGTAA R926: CCGTCAATTCCTTTGAGTTT [25, 26]. The library preparation and sequencing were performed on an Illumina MiSeq platform at Shanghai Personalbio Technology Co., Ltd. according to the standard protocols. The 16S rRNA sequencing data were pre-processed and analyzed using QIIME2 pipeline (v. 2019.6).